CN103305702B - Process for recovering and purifying neptunium from waste liquor discharged from 2AW+2DW in Purex flow - Google Patents
Process for recovering and purifying neptunium from waste liquor discharged from 2AW+2DW in Purex flow Download PDFInfo
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- 229910052781 Neptunium Inorganic materials 0.000 title claims abstract description 74
- LFNLGNPSGWYGGD-UHFFFAOYSA-N neptunium atom Chemical compound [Np] LFNLGNPSGWYGGD-UHFFFAOYSA-N 0.000 title claims abstract description 64
- 238000000034 method Methods 0.000 title claims abstract description 32
- 230000008569 process Effects 0.000 title claims abstract description 22
- 239000002699 waste material Substances 0.000 title claims abstract description 10
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 title claims abstract description 8
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims abstract description 39
- 238000000746 purification Methods 0.000 claims abstract description 32
- 229910052778 Plutonium Inorganic materials 0.000 claims abstract description 31
- 229910052770 Uranium Inorganic materials 0.000 claims abstract description 27
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 23
- OYEHPCDNVJXUIW-UHFFFAOYSA-N plutonium atom Chemical compound [Pu] OYEHPCDNVJXUIW-UHFFFAOYSA-N 0.000 claims abstract description 21
- 239000012074 organic phase Substances 0.000 claims abstract description 20
- 239000007788 liquid Substances 0.000 claims abstract description 19
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 claims abstract description 17
- 239000003350 kerosene Substances 0.000 claims abstract description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 15
- 239000008346 aqueous phase Substances 0.000 claims abstract description 12
- 239000012071 phase Substances 0.000 claims abstract description 9
- QKUTVYUEUPNRBO-UHFFFAOYSA-N [O--].[O--].[Np+4] Chemical compound [O--].[O--].[Np+4] QKUTVYUEUPNRBO-UHFFFAOYSA-N 0.000 claims abstract description 7
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 7
- 229910000478 neptunium(IV) oxide Inorganic materials 0.000 claims abstract description 7
- 239000007787 solid Substances 0.000 claims abstract description 4
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 claims description 44
- 238000000605 extraction Methods 0.000 claims description 26
- 235000011194 food seasoning agent Nutrition 0.000 claims description 13
- MCKSVABBSOFRGC-UHFFFAOYSA-D [Np+5].[Np+5].[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O Chemical compound [Np+5].[Np+5].[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O MCKSVABBSOFRGC-UHFFFAOYSA-D 0.000 claims description 12
- 235000006408 oxalic acid Nutrition 0.000 claims description 12
- CMZUMMUJMWNLFH-UHFFFAOYSA-N sodium metavanadate Chemical compound [Na+].[O-][V](=O)=O CMZUMMUJMWNLFH-UHFFFAOYSA-N 0.000 claims description 10
- 150000002429 hydrazines Chemical class 0.000 claims description 9
- 230000001590 oxidative effect Effects 0.000 claims description 8
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 7
- 229910017604 nitric acid Inorganic materials 0.000 claims description 7
- 239000007800 oxidant agent Substances 0.000 claims description 7
- 239000000047 product Substances 0.000 claims description 7
- 238000001354 calcination Methods 0.000 claims description 6
- 239000003599 detergent Substances 0.000 claims description 6
- WFPZPJSADLPSON-UHFFFAOYSA-N dinitrogen tetraoxide Chemical compound [O-][N+](=O)[N+]([O-])=O WFPZPJSADLPSON-UHFFFAOYSA-N 0.000 claims description 6
- 239000002244 precipitate Substances 0.000 claims description 6
- 230000009467 reduction Effects 0.000 claims description 5
- 239000013078 crystal Substances 0.000 claims description 3
- 238000001704 evaporation Methods 0.000 claims description 3
- 239000012527 feed solution Substances 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 239000012452 mother liquor Substances 0.000 claims description 3
- 238000011084 recovery Methods 0.000 abstract description 10
- 239000003758 nuclear fuel Substances 0.000 abstract description 2
- 238000012805 post-processing Methods 0.000 abstract 1
- 238000001556 precipitation Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 238000005342 ion exchange Methods 0.000 description 3
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- 206010041662 Splinter Diseases 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000002265 redox agent Substances 0.000 description 2
- 238000012958 reprocessing Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- LPXPTNMVRIOKMN-UHFFFAOYSA-M sodium nitrite Chemical compound [Na+].[O-]N=O LPXPTNMVRIOKMN-UHFFFAOYSA-M 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000000638 solvent extraction Methods 0.000 description 2
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 1
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- NTIYJDGGWRWXPJ-UHFFFAOYSA-N NN.NO.O[N+]([O-])=O Chemical compound NN.NO.O[N+]([O-])=O NTIYJDGGWRWXPJ-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000002927 high level radioactive waste Substances 0.000 description 1
- -1 hydrazine nitrate-sodium nitrite Chemical compound 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000003456 ion exchange resin Substances 0.000 description 1
- 229920003303 ion-exchange polymer Polymers 0.000 description 1
- 230000010534 mechanism of action Effects 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 235000010288 sodium nitrite Nutrition 0.000 description 1
- 239000002915 spent fuel radioactive waste Substances 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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Abstract
本发明属于核燃料后处理技术领域，公开了一种从Purex流程的2AW+2DW中放废液中回收和纯化镎的工艺，该工艺包括镎的第一次纯化工艺和镎的第二次纯化工艺，以30%TBP-煤油（体积分数）作为萃取剂，将Np、U、Pu萃取至有机相，裂片元素进入水相，然后在有机相中加入还原剂以及补萃剂将Np反萃至水相，并进一步萃取铀和钚，得到的水相产物经草酸盐沉淀、过滤、煅烧后得到纯化后的二氧化镎固体。该工艺具有镎回收率高达98%以上、镎中去铀、去钚系数高的优点。
The invention belongs to the technical field of nuclear fuel post-processing, and discloses a process for recovering and purifying neptunium from 2AW+2DW waste liquid of Purex process, the process includes the first purification process of neptunium and the second purification process of neptunium , with 30% TBP-kerosene (volume fraction) as the extractant, extract Np, U, Pu to the organic phase, split elements into the water phase, and then add reducing agent and supplementary agent to the organic phase to back-extract Np to the water phase, and further extract uranium and plutonium, and the obtained aqueous phase product is precipitated by oxalate, filtered, and calcined to obtain purified neptunium dioxide solid. This process has the advantages of high recovery rate of neptunium over 98%, high coefficient of removal of uranium and plutonium from neptunium.
Description
技术领域 technical field
本发明属于核燃料后处理技术领域，具体涉及一种从Purex流程的2AW+2DW中放废液中回收和纯化镎的工艺。 The invention belongs to the technical field of nuclear fuel reprocessing, and in particular relates to a process for recovering and purifying neptunium from 2AW+2DW waste liquid of the Purex process. the
背景技术 Background technique
乏燃料中镎含量约为500～700克/吨，其中237Np的辐照产品为238Pu，是重要的α放射源，有着广泛的用途。目前后处理厂提取镎基本上有从高放废液提取和中放废液提取两种途径，提取镎的工艺主要有离子交换法和溶剂萃取法。其中离子交换法的原理是在高浓度硝酸条件下，利用镎、钚、裂片元素与离子交换树脂间的亲和力不同，实现镎、钚与裂片元素的分离；然后使用如二价铁等试剂进行还原解吸钚，最后采用低酸解吸镎，最终实现钚与镎的分离。为了纯化镎，可能还需进行第二次或第三次的循环操作，采用离子交换法的缺点是操作繁琐且产生的废液和废树脂等核废物多。原子能研究所的江浩等公开了《从Purex流程中放废液中回收和纯化镎、钚、铀的研究》，文中公开了利用溶剂萃取法对2AW与2DW中的镎、钚、铀进行回收， TBP作为萃取剂，以过氧化氢，硝酸肼-亚硝酸钠、硝酸肼-硝酸羟胺-发烟硝酸作氧化还原剂，定量萃取镎、钚、铀。但是由于使用的氧化还原剂的种类较多不利于料液的后续处理，而且其选用还原剂中有亚硝酸钠，这也是后处理中不希望使用的有盐还原剂，因此不适合用来纯化和回收镎。 The neptunium content in spent fuel is about 500-700 g/t, and the irradiated product of 237 Np is 238 Pu, which is an important α-radiation source and has a wide range of uses. At present, there are basically two ways to extract neptunium from high-level waste liquid and medium-level waste liquid in reprocessing plants. The main techniques for extracting neptunium are ion exchange method and solvent extraction method. The principle of the ion exchange method is to use the different affinity between neptunium, plutonium, splinter elements and ion exchange resin under the condition of high concentration nitric acid to realize the separation of neptunium, plutonium and splinter elements; and then use reagents such as ferrous iron for reduction The plutonium is desorbed, and the neptunium is finally desorbed with low acid to finally realize the separation of plutonium and neptunium. In order to purify neptunium, a second or third cycle operation may be required. The disadvantage of using the ion exchange method is that the operation is cumbersome and produces a lot of nuclear waste such as waste liquid and waste resin. Jiang Hao from the Institute of Atomic Energy published "Research on the Recovery and Purification of Neptunium, Plutonium, and Uranium from the Waste Liquid in the Purex Process", which disclosed the use of solvent extraction to recover neptunium, plutonium, and uranium in 2AW and 2DW , TBP as extraction agent, with hydrogen peroxide, hydrazine nitrate-sodium nitrite, hydrazine nitrate-hydroxylamine nitrate-fuming nitric acid as redox agent, quantitatively extract neptunium, plutonium and uranium. However, due to the many types of redox agents used, it is not conducive to the subsequent treatment of the feed liquid, and sodium nitrite is selected as the reducing agent, which is also a salty reducing agent that is not expected to be used in the post-treatment, so it is not suitable for purification. and recycled neptunium.
发明内容 Contents of the invention
（一）发明目的(1) Purpose of the invention
根据现有技术所存在的问题，本发明提供了一种镎回收率高达98%以上、镎中去铀、去钚系数高的镎回收和纯化工艺。 According to the problems existing in the prior art, the present invention provides a neptunium recovery and purification process with a neptunium recovery rate as high as over 98%, uranium removal from neptunium, and high plutonium removal coefficient.
（二）技术方案(2) Technical solutions
为了解决现有技术所存在的问题，本发明提供的技术方案如下： In order to solve the existing problems of the prior art, the technical solutions provided by the invention are as follows:
一种从Purex流程的2AW+2DW中放废液中回收和纯化镎的工艺，该工艺包括镎的第一次纯化工艺和镎的第二次纯化工艺，其中镎的第一次纯化工艺包括以下步骤： A process for recovering and purifying neptunium from the 2AW+2DW waste liquid of the Purex process, the process includes the first purification process of neptunium and the second purification process of neptunium, wherein the first purification process of neptunium includes the following step:
（1）将钚萃取槽萃余液2AW和铀萃取槽萃余液2DW蒸发浓缩后，用偏钒酸钠作为氧化剂调料，5～10mol/L HNO3调节酸度，得到待纯化料液2NAF，其中2NAF中包含Np、U、Pu及裂片元素，Np主要以Np（Ⅵ）形式存在； (1) After the plutonium extraction tank raffinate 2AW and the uranium extraction tank raffinate 2DW are evaporated and concentrated, sodium metavanadate is used as the oxidant seasoning, and 5-10mol/L HNO 3 is used to adjust the acidity to obtain the feed liquid 2NAF to be purified, wherein 2NAF contains Np, U, Pu and split elements, and Np mainly exists in the form of Np(Ⅵ);
（2）将2NAF引入镎萃取槽2NA中，2NA中还引入30%TBP-煤油（体积分数）作为萃取剂2NAX，3~4mol/L HNO3作为洗涤剂2NAS，其中U、Np、Pu共同萃取进入有机相2NAP，裂片元素进入水相2NAW； (2) Introduce 2NAF into the neptunium extraction tank 2NA, and introduce 30% TBP-kerosene (volume fraction) into 2NA as the extractant 2NAX, and 3~4mol/L HNO 3 as the detergent 2NAS, where U, Np, and Pu are co-extracted Enter the organic phase 2NAP, and the split elements enter the aqueous phase 2NAW;
（3）将步骤（2）中得到的有机相2NAP作为2NBF引入到镎反萃槽2NB中，2NB槽中还引入0.2~0.5mol/L肼或肼的衍生物—0.2~0.4 mol/L HNO3作为还原反萃剂2NBX，其中还原反萃剂中的肼或肼的衍生物将Np（Ⅵ）还原为Np（Ⅴ），Np从有机相反萃到水相，30%TBP-煤油（体积分数）作为补萃剂2NBS进一步萃取铀、钚，水相产物为2NBP； (3) Introduce the organic phase 2NAP obtained in step (2) into the neptunium stripping tank 2NB as 2NBF, and introduce 0.2~0.5mol/L hydrazine or hydrazine derivative—0.2~0.4 mol/L HNO into the 2NB tank 3 As the reducing stripping agent 2NBX, wherein the hydrazine or hydrazine derivatives in the reducing stripping agent reduce Np(Ⅵ) to Np(Ⅴ), Np is extracted from the organic phase to the water phase, 30% TBP-kerosene (volume fraction ) as a supplementary extraction agent 2NBS to further extract uranium and plutonium, and the aqueous phase product is 2NBP;
镎的第二次纯化工艺包括以下步骤： The second purification process of neptunium includes the following steps:
（1）在2NBP料液中加入液态四氧化二氮，破坏其中的还原剂肼或肼的衍生物，用偏钒酸钠作为氧化剂将Np氧化成六价，用5~10mol/L HNO3调节2NBP中硝酸浓度为4mol/L，然后将2NBP作为3NAF料液进入到镎的第二次纯化工艺的萃取槽3NA中； (1) Add liquid dinitrogen tetroxide to the 2NBP feed solution to destroy the reducing agent hydrazine or hydrazine derivatives, use sodium metavanadate as the oxidant to oxidize Np to hexavalent, and adjust with 5~10mol/L HNO3 The concentration of nitric acid in 2NBP is 4mol/L, then 2NBP is entered in the extraction tank 3NA of the second purification process of neptunium as 3NAF feed liquid;
（2）将3NAF引入镎萃取槽3NA中，3NA中还引入30%TBP-煤油（体积分数）作为萃取剂3NAX，3~4mol/L HNO3作为洗涤剂3NAS，其中U、Np、Pu共同萃取进入有机相3NAP，裂片元素进入水相3NAW； (2) Introduce 3NAF into neptunium extraction tank 3NA, and introduce 30% TBP-kerosene (volume fraction) into 3NA as extractant 3NAX, and 3~4mol/L HNO 3 as detergent 3NAS, where U, Np, and Pu are co-extracted Enter the organic phase 3NAP, and the split elements enter the aqueous phase 3NAW;
（3）将步骤（2）中得到的有机相3NAP作为3NBF引入到镎反萃槽3NB中，3NB槽中还引入0.2~0.5mol/L肼或肼的衍生物—0.2~0.4 mol/LHNO3作为还原反萃剂3NBX，其中还原反萃剂中的肼或肼的衍生物将Np（Ⅵ）还原为Np（Ⅴ），Np从有机相反萃到水相，30%TBP-煤油（体积分数）作为补萃剂3NBS进一步萃取铀、钚，水相产物为3NBP； (3) Introduce the organic phase 3NAP obtained in step (2) into the neptunium stripping tank 3NB as 3NBF, and introduce 0.2~0.5mol/L hydrazine or a derivative of hydrazine—0.2~0.4 mol/LHNO 3 into the 3NB tank As a reducing stripping agent 3NBX, in which the hydrazine or hydrazine derivatives in the reducing stripping agent reduce Np(Ⅵ) to Np(Ⅴ), Np is extracted from the organic phase to the aqueous phase, 30% TBP-kerosene (volume fraction) 3NBS is used as a supplementary extraction agent to further extract uranium and plutonium, and the aqueous phase product is 3NBP;
（4）将3NBP用4~6mol/L HNO3、0.5~0.7mol/L肼或肼的衍生物调料后，加入0.5~1.2 mol/L的草酸并且使草酸过剩0.05~0.15mol/L，在50～60℃条件下得到草酸镎沉淀，并经过滤、煅烧后得到二氧化镎固体； (4) After seasoning 3NBP with 4~6mol/L HNO 3 , 0.5~0.7mol/L hydrazine or hydrazine derivatives, add 0.5~1.2 mol/L oxalic acid and make oxalic acid excess 0.05~0.15mol/L. Neptunium oxalate precipitate was obtained at 50-60°C, and neptunium dioxide solid was obtained after filtration and calcination;
（5）将步骤（4）中过滤后的母液经蒸发浓缩后与2NBP混合，再依次按照步骤（1）、（2）（3）、（4）进行操作。 (5) Mix the mother liquor filtered in step (4) by evaporation and concentration with 2NBP, and then follow steps (1), (2), (3), and (4) in sequence.
优选地，2NAX：2NAF:2NAS的流比、2NBS:2NBF:2NBX的流比为、3NAX:3NAF:3NAS的流比以及3NBS:3NBF:3NBX的流比均为1:3:1。 Preferably, the flow ratios of 2NAX:2NAF:2NAS, 2NBS:2NBF:2NBX, 3NAX:3NAF:3NAS and 3NBS:3NBF:3NBX are all 1:3:1. the
优选地，在第二次纯化工艺的步骤（4）中，所述的煅烧分为三个阶段：第一阶段：温度由室温升至100℃,去除草酸镎沉淀中的自由水；第二阶段：温度在100℃～200℃,去除草酸镎沉淀中的结晶水；第三阶段:300～320℃，草酸镎分解成二氧化镎。 Preferably, in step (4) of the second purification process, the calcination is divided into three stages: the first stage: the temperature rises from room temperature to 100°C to remove free water in the neptunium oxalate precipitate; the second stage Stage: The temperature is 100℃～200℃, and the crystal water in the neptunium oxalate precipitation is removed; the third stage: 300～320℃, the neptunium oxalate is decomposed into neptunium dioxide. the
优选地，第一次纯化工艺的步骤（3）、第二次纯化工艺的步骤（3）中还原反萃剂为0.2~0.5mol/L肼—0.2~0.4 mol/LHNO3，第二次纯化工艺的步骤（4）中用4~6mol/L HNO3、0.5~0.7mol/L肼调料。 Preferably, the reducing stripping agent in step (3) of the first purification process and step (3) of the second purification process is 0.2-0.5 mol/L hydrazine-0.2-0.4 mol/L HNO 3 , the second purification In step (4) of the process, 4-6mol/L HNO 3 and 0.5-0.7mol/L hydrazine are used for seasoning.
（三）有益效果(3) Beneficial effects
本发明提供的回收和纯化镎的工艺，镎的回收率高达98%以上，其还具有以下优点：（1）在两次纯化工艺中，均设计了补萃步骤，即在2NB、3NB槽分别设计了30%TBP-煤油作为补萃剂，可将铀、钚进一步萃取。 The process for recovering and purifying neptunium provided by the present invention has the recovery rate of neptunium as high as 98%, and it also has the following advantages: (1) In the two purification processes, supplementary extraction steps are designed, that is, in the 2NB and 3NB tanks respectively 30% TBP-kerosene is designed as a supplementary extraction agent, which can further extract uranium and plutonium.
（2）在需要将Np由Np（Ⅴ）氧化至Np（Ⅵ）过程中，均加入了偏钒酸钠作为稳定剂和氧化剂，有利于镎回收率的提高。 (2) In the process of oxidizing Np from Np(Ⅴ) to Np(Ⅵ), sodium metavanadate was added as a stabilizer and oxidant, which is beneficial to the improvement of neptunium recovery. the
以第一次纯化工艺的步骤（1）为例，由于在2AW和2DW中镎主要呈四价和五价两种价态，但是镎只有六价形式才能被TBP有效萃取，在以往的工艺中要求99%以上的镎都能被氧化成六价，这在实际操作中是十分困难而且是很难实现的，而本工艺中只需90%以上的镎被氧化成六价即可，同样也可实现98%以上的收率。原因是加入了偏钒酸钠，具体原理为：偏钒酸钠的加入可以将五价镎氧化至六价而且也可以使Np（Ⅵ）的价态稳定，在30%TBP-煤油（体积分数）不断萃取Np（Ⅵ）的过程当中，由于化学平衡关系，Np（Ⅴ）也会不断地被VO3 -氧化成Np（Ⅵ），然后不断地被TBP萃取，所以在2NA槽中99.9%以上的镎均被萃取。在第二次纯化工艺的步骤（1）中也加入了偏钒酸钠，其作用机理与上述相似。 Taking step (1) of the first purification process as an example, neptunium is mainly in two valence states of tetravalent and pentavalent in 2AW and 2DW, but only the hexavalent form of neptunium can be effectively extracted by TBP, in the previous process It is required that more than 99% of neptunium can be oxidized to hexavalent, which is very difficult and difficult to achieve in actual operation, but in this process, only more than 90% of neptunium should be oxidized to hexavalent. A yield of more than 98% can be achieved. The reason is the addition of sodium metavanadate. The specific principle is: the addition of sodium metavanadate can oxidize pentavalent neptunium to hexavalent and also stabilize the valence state of Np (Ⅵ). In 30% TBP-kerosene (volume fraction ) in the process of continuously extracting Np(Ⅵ), due to the chemical balance, Np(Ⅴ) will also be continuously oxidized by VO 3 - to Np(Ⅵ), and then continuously extracted by TBP, so more than 99.9% in the 2NA tank Neptunium was extracted. Sodium metavanadate is also added in step (1) of the second purification process, and its mechanism of action is similar to the above.
附图说明 Description of drawings
图1是从2AW+2DW中回收和纯化Np的工艺流程图； Fig. 1 is the process flow diagram of recovering and purifying Np from 2AW+2DW;
图2是Np的第一次纯化工艺图； Fig. 2 is the first purification process diagram of Np;
图3是Np的第二次纯化工艺图。 Fig. 3 is the second purification process diagram of Np.
具体实施方式 Detailed ways
下面结合说明书附图和具体实施方式对本发明做进一步阐述。 The present invention will be further elaborated below in conjunction with the accompanying drawings and specific embodiments. the
实施例1Example 1
将实验台架安装于手套箱内，对钚萃取槽萃余液2AW和铀萃取槽萃余液2DW料液中的镎进行回收和纯化，其操作步骤为： The experimental bench is installed in the glove box, and the neptunium in the plutonium extraction tank raffinate 2AW and the uranium extraction tank raffinate 2DW feed liquid is recovered and purified, and the operation steps are as follows:
（1）将钚萃取槽萃余液2AW和铀萃取槽萃余液2DW蒸发浓缩后，用偏钒酸钠作为氧化剂调料，5mol/L的HNO3调节酸度，得到待纯化料液2NAF，其中2NAF中包含Np、U、Pu及裂片元素，Np主要以Np（Ⅵ）形式存在； (1) After the plutonium extraction tank raffinate 2AW and the uranium extraction tank raffinate 2DW are evaporated and concentrated, sodium metavanadate is used as the oxidant seasoning, and 5mol/L HNO 3 is used to adjust the acidity to obtain the feed liquid 2NAF to be purified, of which 2NAF Contains Np, U, Pu and split elements, and Np mainly exists in the form of Np (Ⅵ);
（2）将2NAF引入镎萃取槽2NA中，2NA中还引入30%TBP-煤油（体积分数）作为萃取剂2NAX，3mol/L HNO3作为洗涤剂2NAS，其中U、Np、Pu共同萃取进入有机相2NAP，裂片元素进入水相2NAW，2NAX：2NAF:2NAS的流比为1:3:1。 (2) 2NAF was introduced into neptunium extraction tank 2NA, 30% TBP-kerosene (volume fraction) was also introduced into 2NA as extractant 2NAX, and 3mol/L HNO 3 was used as detergent 2NAS, in which U, Np and Pu were co-extracted into the organic Phase 2NAP, split elements into the aqueous phase 2NAW, 2NAX:2NAF:2NAS flow ratio is 1:3:1.
（3）将步骤（2）中得到的有机相2NAP作为2NBF引入到镎反萃槽2NB中，2NB槽中还引入0.2mol/L肼—0.2 mol/LHNO3作为还原反萃剂2NBX，其中还原反萃剂中的肼将Np（Ⅵ）还原为Np（Ⅴ），Np从有机相反萃到水相，30%TBP-煤油（体积分数）作为补萃剂2NBS进一步萃取铀、钚，水相产物为2NBP，2NBS:2NBF:2NBX的流比为1:3:1； (3) The organic phase 2NAP obtained in step (2) is introduced as 2NBF into neptunium stripping tank 2NB, and 0.2mol/L hydrazine—0.2mol/ LHNO3 is also introduced into the 2NB tank as the reducing stripping agent 2NBX, wherein the reducing Hydrazine in the stripping agent reduces Np(Ⅵ) to Np(Ⅴ), Np is extracted from the organic phase to the water phase, and 30% TBP-kerosene (volume fraction) is used as a supplementary extraction agent 2NBS to further extract uranium, plutonium, and the water phase product For 2NBP, the flow ratio of 2NBS:2NBF:2NBX is 1:3:1;
镎的第二次纯化工艺包括以下步骤： The second purification process of neptunium includes the following steps:
（1）在2NBP料液中加入液态四氧化二氮，破坏其中的还原剂肼，用偏钒酸钠作为氧化剂将Np氧化成六价，用5mol/L HNO3调节2NBP中硝酸浓度为4mol/L，然后将2NBP作为3NAF料液进入到镎的第二次纯化工艺的萃取槽3NA中； (1) Add liquid dinitrogen tetroxide to the 2NBP feed solution to destroy the reducing agent hydrazine, use sodium metavanadate as the oxidant to oxidize Np to hexavalent, and use 5mol/L HNO3 to adjust the concentration of nitric acid in 2NBP to 4mol/L L, then 2NBP enters in the extraction tank 3NA of the second purification process of neptunium as 3NAF feed liquid;
（2）将3NAF引入镎萃取槽3NA中，3NA中还引入30%TBP-煤油（体积分数）作为萃取剂3NAX，3mol/L HNO3作为洗涤剂3NAS，其中U、Np、Pu共同萃取进入有机相3NAP，裂片元素进入水相3NAW，3NAX:3NAF:3NAS的流比为1:3:1； (2) 3NAF was introduced into neptunium extraction tank 3NA, 30% TBP-kerosene (volume fraction) was also introduced into 3NA as extractant 3NAX, 3mol/L HNO 3 was used as detergent 3NAS, in which U, Np and Pu were co-extracted into the organic Phase 3NAP, split elements enter the aqueous phase 3NAW, the flow ratio of 3NAX:3NAF:3NAS is 1:3:1;
（3）将步骤（2）中得到的有机相3NAP作为3NBF引入到镎反萃槽3NB中，3NB槽中还引入0.2mol/L肼—0.2 mol/LHNO3作为还原反萃剂3NBX，其中还原反萃剂中的肼将Np（Ⅵ）还原为Np（Ⅴ），Np从有机相反萃到水相，30%TBP-煤油（体积分数）作为补萃剂3NBS进一步萃取铀、钚，水相产物为3NBP，3NBS:3NBF:3NBX的流比均为1:3:1； (3) Introduce the organic phase 3NAP obtained in step (2) into the neptunium stripping tank 3NB as 3NBF, and introduce 0.2mol/L hydrazine—0.2mol/ LHNO3 into the 3NB tank as the reducing stripping agent 3NBX, wherein Hydrazine in the stripping agent reduces Np(Ⅵ) to Np(Ⅴ), Np is extracted from the organic phase to the water phase, and 30% TBP-kerosene (volume fraction) is used as a supplementary extraction agent 3NBS to further extract uranium, plutonium, and the water phase product For 3NBP, the flow ratio of 3NBS:3NBF:3NBX is 1:3:1;
（4）将3NBP用4mol/L HNO3、0.5mol/L肼调料后，加入0.5 mol/L的草酸并且使草酸过剩0.05mol/L，在50℃条件下得到草酸镎沉淀，并经过滤、煅烧后得到二氧化镎固体；所述的煅烧分为三个阶段：第一阶段：温度由室温升至100℃,去除草酸镎沉淀中的自由水；第二阶段：温度在100℃～200℃,去除草酸镎沉淀中的结晶水；第三阶段:300～320℃，草酸镎分解成二氧化镎。 (4) After seasoning 3NBP with 4mol/L HNO 3 and 0.5mol/L hydrazine, add 0.5 mol/L oxalic acid and make the excess oxalic acid 0.05mol/L, obtain neptunium oxalate precipitate at 50℃, and filter, Neptunium dioxide solids are obtained after calcination; the calcination is divided into three stages: the first stage: the temperature rises from room temperature to 100°C to remove free water in the neptunium oxalate precipitation; the second stage: the temperature is between 100°C and 200°C ℃, to remove crystal water in neptunium oxalate precipitation; third stage: 300-320℃, neptunium oxalate decomposes into neptunium dioxide.
（5）将步骤（4）中过滤后的母液经蒸发浓缩后与2NBP混合，再依次按照步骤（1）、（2）（3）、（4）进行操作。 (5) Mix the mother liquor filtered in step (4) by evaporation and concentration with 2NBP, and then follow steps (1), (2), (3), and (4) in sequence. the
台架试验结果为：镎的回收率为99.92%。 The bench test results are: the recovery rate of neptunium is 99.92%. the
实施例2Example 2
与实施例1中的操作步骤和方法相同，不同的是调料浓度、还原剂浓度等参数变化，具体如下表： The operation steps and method are the same as in Example 1, except that the parameters such as seasoning concentration and reducing agent concentration change, as shown in the following table:
表1参数表 Table 1 parameter list
实施例3 Example 3
与实施例1中的操作步骤和方法相同，不同的是第二次纯化工艺的步骤（4）中的调料参数及草酸浓度，具体为将3NBP用5mol/L HNO3、0.6 mol/L 肼调料，加入1.0mol/L草酸并使草酸过剩0.1mol/L，进行草酸盐沉淀，镎的回收率为99.91%。 The operation steps and methods are the same as those in Example 1, the difference is the seasoning parameters and oxalic acid concentration in step (4) of the second purification process, specifically seasoning 3NBP with 5 mol/L HNO 3 , 0.6 mol/L hydrazine , add 1.0mol/L oxalic acid and make oxalic acid excess 0.1mol/L, carry out oxalate precipitation, the recovery rate of neptunium is 99.91%.
实施例4Example 4
与实施例1中的操作步骤和方法相同，不同的是第二次纯化工艺的步骤（4）中的调料参数及草酸浓度，具体为将3NBP用6mol/L HNO3、0.7 mol/L 肼调料，加入1.2mol/L草酸并使草酸过剩0.15mol/L，进行草酸盐沉淀，镎的回收率为99.91%。 The operation steps and methods are the same as those in Example 1, the difference is the seasoning parameters and oxalic acid concentration in step (4) of the second purification process, specifically seasoning 3NBP with 6mol/L HNO 3 and 0.7 mol/L hydrazine , add 1.2mol/L oxalic acid and make oxalic acid excess 0.15mol/L, carry out oxalate precipitation, the recovery rate of neptunium is 99.91%.
实施例5Example 5
与实施例1所用方法和步骤相同，不同的是用肼的衍生物代替实施例1中的肼，台架试验结果为：镎的回收率为99.83%。 The method and steps used in Example 1 are the same, except that hydrazine derivatives are used instead of hydrazine in Example 1. The bench test results are: the recovery rate of neptunium is 99.83%.
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